Computational study of the GMDPO dual phase-1 algorithm

Maros's GDPO algorithm for phase-1 of the dual simplex method possesses some theoretical features that have potentially huge computational advantages. This paper gives account of a computational analysis of GDPO. Experience of a systematic study involving 48 problems shows that the predicted performance advantages can materialize to a large extent making GDPO an indispensable tool for dual pahase-1

An enhanced piecewise linear dual phase-1 algorithm for the simplex method

A dual phase-1 algorithm for the simplex method that handles all types of vari- ables is presented. In each iteration it maximizes a piecewise linear function of dual infeasibilities in order to make the largest possible step towards dual feasibility with a selected outgoing variable. The algorithm can be viewed as a generalization of traditional phase-1 procedures. It is based on the multiple use of the expensively computed pivot row. By small amount of extra work per iteration, the progress it can make is equivalent to many iterations of the traditional method. While this is its most important feature, it possesses some additional favorable properties, namely, it can be efficient in coping with degeneracy and numerical difficulties. Both theo- retical and computational issues are addressed. Some computational experience is also reported which shows that the potentials of the method can materialize on real world problems. This paper is based on IC Departmental Technical Report 2000/13 and contains an enhancement of the main algorithm

An enhanced piecewise linear dual phase-1 algorithm for the simplex method

A dual phase-1 algorithm for the simplex method that handles all types of vari- ables is presented. In each iteration it maximizes a piecewise linear function of dual infeasibilities in order to make the largest possible step towards dual feasibility with a selected outgoing variable. The algorithm can be viewed as a generalization of traditional phase-1 procedures. It is based on the multiple use of the expensively computed pivot row. By small amount of extra work per iteration, the progress it can make is equivalent to many iterations of the traditional method. While this is its most important feature, it possesses some additional favorable properties, namely, it can be e cient in coping with degeneracy and numerical di culties. Both theo- retical and computational issues are addressed. Some computational experience is also reported which shows that the potentials of the method can materialize on real world problems. This paper is based on IC Departmental Technical Report 2000/13 and contains an enhancement of the main algorithm

A BI-REGIONAL CGE MODEL OF THE SOUTH WEST HOUSING MARKET

Volatility within the UK housing market is thought to be a significant factor driving instability in the wider macro economy. Research investigating the characteristics and behaviour of the housing market has suggested that under supply of housing is one of the key reasons for the high and increasing levels of house prices the nation has recently been experiencing. Consequently, much of the current government's housing policy is aimed at increasing the level of supply by reforming the planning system and increasing investment in the development of new housing. Under supply is also a major concern at the regional level, particularly in the South West, where net inward migration, growth in the number of single person households and growth in the numbers of second homes is placing increasing pressure on the housing market. Understanding the likely effects of any policy changes prior to their implementation is vitally important for a successful outcome and to that end economic analysis has played a significant role in the development of policy at the national level. However, this is not the case at the regional and sub-regional levels where only limited use of economic analysis techniques have been made, partly due to resource issues and partly due to the lack of regional data. In order to partially address the lack of analysis of the regional impacts of the latest housing policies, this study is based upon the development of a mathematical economic model of the South West housing market. This model is then used to estimate the likely impacts of increasing housing supply at both the regional and broad sub-regional levels

Real exchange rate misalignments and economic growth in Sub-Saharan African countries

This study examined the effect of real exchange rate misalignments on economic growth in sub-Saharan Africa (SSA) by employing 15 countries. The sample is subdivided into 7 lowincome countries and 8 middle-income countries. The dataset spans 41 years covering the period 1970-2010. The study examined this broad issue in piecewise fashion. In the first part, the study examined the validity of the Balassa-Samuelson Hypothesis (BSH) using a simplified regression model and within-effects estimations. The study found a negative and highly significant coefficient of the relative productivity term for the two subsamples (i.e. low-income SSA countries and middle-income SSA countries), in addition to the full sample. Thus, the study found a well-established BSH for the SSA countries considered. Second, the study examined the impact of the real exchange rate undervaluation on economic growth using a standard regression model with key control variables. The study constructed an index of undervaluation, following Rodrik (2008). The study also constructed a Hodrick- Prescott based undervaluation index in order to evaluate the robustness of the main undervaluation index. Generally, the study found undervaluation to promote growth and overvaluation to reduce it. The study found the effect of undervaluation on economic growth to weaken as countries migrate from the low-income bracket to the middle-income bracket. Moreover, the study examined whether the choice of the undervaluation measure mattered. The study found the choice of the undervaluation measure to matter. The Rodrik-type index appeared to overestimate the size of the impact of undervaluation on economic growth. Finally, the study examined whether the impact of undervaluation on growth was linear. The evidence showed that the impact of undervaluation on growth was linear, at least, for this study. The linear impact of real exchange rate movements on economic growth implied that undervaluation enhanced economic growth just as overvaluation hindered it.EconomicsD. Phil. (Economics

Three essays on the Return on investment in human capital of skilled immigrants in Quebec and internal labor migration in developing countries

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2018-2019Cette thèse de doctorat s’intéresse à la migration interne et internationale. Dans un premier temps, je m’intéresse à l’intégration professionnelle des immigrants de la catégorie des travailleurs qualifiés au Québec. Le Québec comme la plupart des autres provinces du Canada, sélectionnent leurs immigrants sur la base de caractéristiques particulières telles que le niveau d’éducation, l’expérience professionnelle, les compétences en français et ou en anglais. Ces compétences devraient faciliter l’insertion professionnelle de ces immigrants et il est donc surprenant de voir que près de la moitié d’entre eux retournent aux études une fois arrivés au Québec afin d’obtenir un diplôme universitaire ou collégial. De ce fait, les deux premiers chapitres de cette thèse s’attèlent à comprendre pourquoi ces immigrants, malgré une telle dotation en capital humain à l’entrée du marché du travail Québécois, décident de retourner aux études et quels sont les effets de cet investissement en éducation tout d’abord sur les fréquences d’emplois et les durées en emploi et ensuite, sur le profil de revenus. Dans un deuxième temps, cette thèse s’intéresse à la participation à la migration interne en Ouganda et l’effet de cette participation sur la productivité agricole des ménages vivant en milieu rural. Le premier chapitre s’intéresse à l’effet dynamique de la formation post-migratoire sur l’offre de travail des immigrants. A cet effet, je fais la distinction entre un emploi qualifié et un emploi non qualifié. Ici, un emploi qualifié est celui-là qui correspond au plus haut diplôme obtenu par l’immigrant à l’entrée. J’utilise un modèle de durée à plusieurs états et à plusieurs épisodes qui permet de tenir compte de l’hétérogénéité observable et inobservable entre les individus. Le principal résultat révèle que les immigrants originaires de pays riches n’ont pas besoin d’investir davantage dans l’éducation Québécoise. En revanche, les immigrants originaires de pays pauvres quant à eux, bien que hautement qualifiés, bénéficient largement d’une telle formation à long terme car cela facilite leur transition vers des emplois qualifiés et non qualifiés et hors du chômage. Mes résultats indiquent également que la sélection dans l’éducation doit être prise en compte afin d’éviter des problèmes de sélection significatifs. À la différence du premier où on suppose que l’effet causal de la formation est le même pour chaque individu, le deuxième chapitre quant à lui s’intéresse à l’hétérogénéité de l’effet causal de la formation sur les revenus. Autrement dit, pour chaque individu il est possible d’estimer un effet moyen en comparant son revenu dans le cas où il a obtenu un diplôme au Québec avec la situation où il n’aurait pas eu un diplôme au Québec, et vice-versa. Ceci est possible grâce à l’introduction de l’approche bayésienne dans l’analyse d’évaluation d’impact mettant en exergue l’estimation du contre-factuel de la variable d’intérêt. Les principaux résultats révèlent que les gains de l’éducation acquise au Québec par rapport à ceux de l’éducation acquise à l’étranger diffèrent d’un immigrant à l’autre. En outre, il y a un gain négatif à entreprendre des études au Québec pour tous les immigrants. Particulièrement, plus la probabilité d’entreprendre des études au Québec est élevée plus le retour sur investissement est faible. Il semblerait que les employeurs rémunèrent les immigrants non pas seulement par rapport à leur diplôme or sa provenance mais aussi par rapport à la qualité de leur précédent emploi. Ainsi, on s’attendrait à ce que les immigrants, toute suite après leur formation, acceptent un emploi relativement moins rémunéré que celui qu’il aurait eu étant donné son éducation. Par ailleurs, bien que l’approche bayésienne suggère que, comparativement aux immigrants qui ont obtenu un diplôme collégial au Québec, ceux qui obtiennent un diplôme universitaire sont les plus négativement affectés par un tel investissement en éducation, l’approche Fréquentiste suggère que ces derniers obtiennent le meilleur rendement des études acquises au Québec. Cela soulève à nouveau la question du biais de sélection qui peut subvenir lorsque l’hétérogénéité de l’effet n’est pas prise en compte. Le troisième chapitre a pour objectif d’estimer la distribution de l’effet dynamique de la participation des ménages à la migration interne de la main d’œuvre sur la productivité agricole. Les résultats révèlent que même si en moyenne la migration interne affecte positivement la productivité agricole, il y a des ménages pour lesquels l’effet est négatif. De plus, les ménages pour qui l’effet est négatif sont pour la plupart de petits agriculteurs et sont par conséquent plus susceptibles d’être pauvres et donc plus susceptibles d’être sujet à la volatilité des prix au niveau local. Par ailleurs, l’effet moyen de la migration tend à augmenter avec la probabilité de participer à la migration interne signifiant que les individus décident de participer à la migration parce qu’ils anticipent des gains futurs plus élevés. Parallèlement, j’examine dans quelle mesure les taux de migration antérieurs, largement utilisés dans la littérature en tant qu’instrument de la décision de participer à la migration, sont exogènes à la productivité agricole. Les résultats suggèrent que ces variables ne sont pas exogènes car elles sont intimement corrélées avec la productivité agricole.This doctoral thesis is interested in international and internal migration. First, it focuses on the professional integration of immigrants in the category of skilled workers in Quebec. Quebec is one of the ten provinces of Canada that, like most other provinces, implemented a program back in 1996 that explicitly selected highly qualified workers based on particular characteristics such as the level of education (Bachelors’, Masters’ or PhD’s), work experience, French and/or English proficiency. Despite these skills that should facilitate their professional integration, 48% of immigrants return to school once they arrive in Quebec in order to obtain a university or college diploma. The first two chapters of this thesis investigates why these immigrants decide to go back to school with such an endowment of human capital and what the effects of this investment in education are on the job frequencies and job durations and, on the earnings profile. This thesis then focuses on the households participation in internal labor migration and the dynamic effect of this participation on the agricultural productivity of households living in rural area of Uganda. The first chapter investigates the extent to which the return to foreign-acquired human capital is different from the education acquired in Quebec. Specifically, it seeks to estimate the benefits of post-migration education over foreign-education on the transitions between qualified and unqualified jobs and unemployment by means of a multiple-spells and multiplestates model. Here, a qualified job is one that corresponds to the highest degree obtained by the immigrant before they come in Quebec. The main results suggest that immigrants originating from well-off countries have no need to further invest in domestic education. Meanwhile, immigrants from poor countries, despite being highly qualified, benefit greatly from such training in the long run as it eases their transitions into qualified and unqualified jobs and out of unemployment. Our results also indicate that selection in education must be taken into account in order to avoid significant selection problems. Unlike the first chapter in which only the average effect of schooling is estimated, the goal of the second chapter is to estimate the distribution of the causal effect of Quebec-acquired education on migrants’ earnings. In other words, it is possible to estimate an average effect for each individual by comparing his income in the case he has obtained a Quebec diploma to the situation where he has not obtained a diploma from Quebec, and vice versa. This is possible thanks to the introduction of the Bayesian approach in the treatment analysis allowing to account for the heterogeneity of the effect. The main results reveal that on average and for each immigrant, there is a negative gain to study in Quebec. However, the magnitude of the effect differs from one immigrant to another. Particularly, the gains tend to decrease with the likelihood of enrolling in school and with the level of ability. Thus, our results suggest that employers pay migrants not only based on their level of education or its origin but more importantly based on the quality of prior jobs held. Furthermore, one would expect immigrants to accept, right after their training, a relatively less paid job than the one he would have had given his education. While the Bayesian approach suggests that immigrants who have enrolled to obtain a university degree are the most negatively affected, the Frequentist approach suggests that those immigrants obtain the highest positive return from Quebec-acquired education. This raises again the issue of mis-evaluation when the essential heterogeneity is not taking into account. The goal of the third chapter is to estimate the distribution of the dynamic effect of household participation in internal labor migration on agricultural productivity in Uganda. Since household can have both observed and unobserved factors that can affect both the decision to participate or not in migration and the return from it, this study account for the heterogeneity of the effect. Results reveal that although, on average, internal labor migration positively affects agricultural productivity, there are households for which the effect is negative. In addition, households for which the effect is negative are mostly small farmers, therefore more likely to be poor and more likely to be subject to local price volatility. It seems that return to migration helps poor household to meet other needs. Moreover, the average effect of migration tends to increase with the probability of participating in internal migration, meaning that households decide to participate in migration because they anticipate higher future returns. At the same time, we also examine the extent to which past migration rates, widely used in the literature as an instrument for the decision to participate in migration, are exogenous to agricultural productivity. Results show that these variables are not exogenous because they are highly correlated with agricultural productivity

Middle Atmosphere Program. Handbook for MAP. Volume 14: URSI/SCOSTEP Workshop on Technical Aspects of MST Radar

Various topics relative to middle atmosphere research were discussed. meteorological and aeronomical requirements for mesosphere-stratosphere-troposphere (MST) radar networks, general circulation of the middle atmosphere, the interpretation of radar returns from clear air, spaced antenna and Doppler techniques for velocity measurement, and techniques for the study of gravity waves and turbulence are among the topics discussed

Computational study of the GDPO dual phase-1 algorithm

Linear programming, Dual simplex, Phase-1, Piecewise linear,